I was just reading about experiments in Italy growing wild Galapagos tomatoes in high salinity water as a possible crop for marine fish aquaponics. Hmm, I always wondered about whether it could one day be done without having to use marine algae. Perhaps marine fish and terrestrial vegetables are a possibility after all.

Hi have planted my tomatoes but they keep turning purple and they not growing i need help....

Phosphorous deficiency. Try swapping your fish feed or adding espsom salts. Best to start with different feed if possible, treat the cause not the symptom as you'll probably find that you have other deficiencies as well.

I did a bit more reading on seawater irrigation for vegetables (mostly from "development of halophyte-based agriculture:past and present:Annals of Botany:Oxford Academic".Boyko and Boyko 1964 started off with the idea that a combination of good drainage and excess seawater irrigation may allow seawater agriculture. This sounds pretty much like marine AP to me. The main problem faced was that very few varieties of halophyte vegetables were developed, despite lots of research effort. Later efforts (after 2000) used naturally salt tolerant plants from saline environments with much more success.species found to be useable were:Crythmum maritimum, Portulaca olearacea, Salicornia and Sarcocornia sps, Aster tripolium, Quinoa, Salsola soda, Crambe maritima, Tetragonia tetragonioides, Beta maritima crithmoides and Mesembryanthum crystallinum.Quite a few of these are already sought after in various restaurant trades world wide, especially as succulent shoots which can be continually harvested throughout the year.Problems arise though with excess nitrates as some will develop undesirable flavours due to Oxalates, nitrates or saponins. In each case, irrigation with NH4 (Ammonium ion) reduced these factors. I'm not suggesting pure seawater AP would be easy or even doable, but producing estuarine fish with various salinities could certainly be possible with a combination of some of these plants.

Cobia are being farmed now en masse in Northern Australia. Good point re hospital tank. Growing plants from a hospital tank with high salinity is something I didn't think of. If you had a large enough turn over of fish and needed regular isolation of new recruits, you might be able to do that and have enough nutrient input to keep the halophytic plants growing. There are a lot of estuarine fish species to choose from worldwide which could fetch a decent price for a regular supply.I was also thinking of how high salinity groundwater might be put to use. Although I live in a cooler part of Oz, the world's largest barramundi aquaculture farm is only a 20min drive from here. They use warm groundwater pumped up from depth to grow these warm water fish, but most of this area has high salinity groundwater (often 8 - 10% NaCl). If they were to add an aquaponic side to their production line, these plants could be a possible extra income plus possibly reduce their wastewater disposal needs.

Another thought might be to grow purslane (Portulaca olearacea) in a high salinity AP system purely to produce Omega 3 and 6 food for SPs or Jade perch. P. olearacea supposedly has the highest omega 3 level of any leafy vegetable and lack of omega 3 in the food of farmed fish is quite a concern for aquacultural producers who do not want to use wild caught fish meal. Being omnivorous, our native perch are ideal for this use of saline aquaponics.

Good point Dangerous Dave. Supplying purslane is one thing, but getting them to eat it is another altogether. Maybe some of the other halophytes listed above could work. Good to hear that they like sweet potato vine as I have plenty and quite like the young leaves myself. My SPs love parsley but less keen on lettuce.

'Maybe they'd be less fussy if they were hungry enough!'

Don't want to leave my fish that hungry LOL. Better to find something else that they like and still supply omega 3.

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